Electronics has hitherto placed its basis on a charge of an electron. However, since an electron has a spin as its other attribute besides its charge and in recent years the limits of electronics placed its basis on the charge have begun to be seen, researches and developments have rapidly been put forward on spintronics, namely spin electronics, which is based on the spin of an electron.
For example, as a device utilizing a spin there is now a GMR (Giant Magneto Resistance) device, which has been put to practical use as a read-out device for magnetic hard disk memories, making it possible to achieve their present level storage capacity. There is also as a third-generation spintronic device a MRAM (Magneto Resistive Random Access Memory) using TMR (Tunnel Magneto Resistance) effect. The MRAM is being put to practical use as a next-generation nonvolatile memory that is low in power consumption, fast in reading and writing, and highly integrated.
In the spintronics, however, there have not yet been realized a conductor for passing a spin current (spin-polarized current) and a switch for turning on and off a spin current, which are corresponding to an electric current conductor and an electric current switch such as FET respectively. For example, while it has been proposed to utilize spin-injection from a ferromagnetic metal into a semiconductor, a problem of losing spin information upon the spin-injection remains unsolved and the prospect of its utilization can not still be foreseen.
In view of the problem mentioned above, the present invention has for its objects to provide a surface-spintronic spin conducting device that is capable of flowing a spin current based on a novel principle of operation, to provide a surface-spintronic spin switching device that is capable of switching a spin current with low power consumption, rapidly and efficiently, and to provide a surface-spintronic spin memory device utilizing the same.